The present invention relates to a high voltage pulse detector for sensing a voltage higher than a circuit supply voltage applied to a circuit terminal and for outputting a logic level signal in the latter case.
Traditionally it has been the practice to use an isolation transistor between an input line and an output line together with series connected diodes to establish a threshold with respect to the supply voltage above which an input voltage will produce an output signal indicating the presence of an input voltage greater than the supply voltage. The output signal must be at a logic level in order to protect subsequent devices. The problem with the foregoing approach has been due to the relatively high uncertainty of the threshold due to the effects of varying temperature and other factors and the dramatic increase of current consumption with increasing input voltage above the threshold.
Accordingly, it is a principal object of the present invention to provide an improved circuit for sensing the presence of an input voltage greater than the limit voltage.